This invention relates to a tie plate placing vehicle and associated method of placing tie plates.
When laying a new railroad track or when laying new rails upon a previously existing railroad track, it is necessary to provide tie plates upon the railroad ties. One tie plate is required for each side of each tie and typically more than three thousand tie plates would be required for one mile of track.
The tie plates may be manually placed upon each of the ties after the tie plates have been placed in piles along side the track. Typically, the tie plates are distributed by a crane having a magnetic head which drops piles of tie plates along side the track. The distance between the piles depends upon the average number of tie plates carried by the magnetic head of the crane. A work gang of about 10 to 15 persons would take tie plates from the pile and properly position them upon the railroad ties. Considering that the tie plates weigh about 28 pounds each and that the tie plates should be placed in the proper position on the tie, it will be appreciated that this method of placement involves high labor costs, inconsistent accuracy of placement, and a time consuming process.
Various machines have been developed in an attempt to avoid the manual method of tie plate placement. In particular, U.S. Pat. No. 3,943,858 issued to Dieringer et al on Mar. 16, 1976 and U.S. Pat. No. 4,241,663 issued to Lund et al on Dec. 30, 1980 show such machines.
The Dieringer et al patent shows a tie plate placement arrangement using a finger for sensing tie position. Upon detection of a tie, the machine is designed to stop over each tie and operate gating fingers to drop each tie plate upon the corresponding tie. A track mechanism may be used to support one side of the vehicle and a conveyor belt arrangement is used for conveying tie plates on the machine.
The Lund et al patent shows an arrangement in which tie plates are placed upon ties by a device including a chute. Tie plates are gated into the chute and an electromagnet is used to hold a tie plate in position such that it will be properly dropped over a tie as determined by a limit switch which is tripped by contact of a tie detector with a tie.
There have been a number of problems associated with various of the prior art methods and devices for distribution of tie plates along ties.
The manual method of tie plate distribution is subject to high labor costs, inconsistent accuracy of placement, and relative slow speed of tie plate distribution, whereas the prior machines for tie plate distribution are often subject to the last two disadvantages. More specifically, the machines often rely upon dropping of tie plates onto the tie such that the placement accuracy is limited by this factor. Additionally, machines which must stop in order to drop or place a tie plate are generally slow in placing tie plates along a given stretch of railroad track, whereas plate placing machines which drop the ties while the machine is moving are often subject to greater inaccuracy.
Various of the prior art plate placing machines have been quite complex in construction and, therefore, relatively expensive.
Prior placer machines which require electro magnets typically require relatively high power electric energy sources.